Control of oocyte maturation in sexually mature Drosophila females

In many sexually mature insects egg production and oviposition are tightly coupled to copulation. Sex-Peptide is a 36-amino-acid peptide synthesized i n the accessory glands of Drosophila melanogaster males and transferred to the female during copulation. Sex-Peptide stimulates vitellogenic oocyte pr ogression through a putative control point at about stage 9 of oogenesis. H ere we show that application of the juvenile hormone analogue methoprene mi mics the Sex-Peptide-mediated stimulation of vitellogenic oocyte progressio n in sexually mature virgin females. Apoptosis is induced by 20-hydroxyecdy sone in nurse cells of stage 9 egg chambers at physiological concentrations (10(-7) M). 20-Hydroxyecdysone thus acts as an antagonist of early vitello genic oocyte development. Simultaneous application of juvenile hormone anal ogue, however, protects early vitellogenic oocytes from 20-hydroxyecdysone- induced resorption. These results suggest that the balance of these hormone s in the hemolymph regulates whether oocytes will progress through the cont rol point at stage 9 or undergo apoptosis. These data are further supported by a molecular analysis of the regulation of yolk protein synthesis and up take into the ovary by the two hormones. We conclude that juvenile hormone is a downstream component in the Sex-Peptide response cascade and acts by s timulating vitellogenic oocyte progression and inhibiting apoptosis. Since juvenile hormone analogue does not elicit increased oviposition and reduced receptivity, Sex-Peptide must have an additional, separate effect on these two postmating responses, (C) 1999 Academic Press.